- From: Steve Harris <S.W.Harris@ecs.soton.ac.uk>
- Date: Wed, 2 Jun 2004 15:37:20 +0100
- To: DAWG public list <public-rdf-dawg@w3.org>
This is the other side of the "bandwidth" problem. I think it completes "ACTION: SteveH to write his experiences on bandwidth efficiency for querying and email to group." The problems I've given myself with increased latency are basically down to overly verbose return formats (again) and things that require the server, and/or client to have to whole result set before it can start work. In 3store the result set is implicitly DISTINCT'd (ie. each unique matching binding row is only returned once) - this was done at users request, but with hindsight it would have been better to add a DISTINCT keyword that turned it on selectively. In practise the server has to hold a copy of the result set while it's returning results, to ensure it doesn't send duplicates. That doesn't add much latency in theory, but the most efficient way of implementing it that we found builds a list then sends the whole lot after all the results have been gathered. In any case it adds some load to the server. Another example would be result set sorting, which again requires the server to hold the result set. Ditto for RDF/XML or any other format that requires prefixes at the top of the file. Some of the clients only have DOM XML parsers, and so they have to wait for the whole XML result set to be returned before they can start processing - we cant help that, but adding things like SQL LIMIT means that they can work on smaller sets. - Steve
Received on Wednesday, 2 June 2004 10:37:22 UTC